Method of using nanofiltration and reverse osmosis to remove chemical contaminants

ABSTRACT

A method of removing chemical contaminants from a composition comprising an active, a solvent, and a contaminant can include providing an initial feed supply, wherein the initial feed supply comprises the active, the solvent, and the contaminant, wherein the contaminant can include 1,4 dioxane, dimethyl dioxane, or a combination thereof; including filtering the initial feed stock through a nanofilter and using reverse osmosis.

FIELD OF THE INVENTION

This application relates generally to processes and apparatus forremoving chemical contaminants. More particularly, it relates theprocesses and apparatus for removing a chemical contaminant, likedioxane, from a surfactant containing composition.

BACKGROUND OF THE INVENTION

Chemical contaminants are sometimes found in raw materials or productsutilizing raw materials. For example, 1,4-dioxane is an undesirablebyproduct of detergent making. As an industrial processing solvent orchemical intermediate, 1,4-dioxane has previously been reported to beused in the production of products that may have commercial or consumerapplications such as paints, adhesives, detergents, and pesticides. Assuch 1,4-dioxane may be present as a contaminant in consumercosmetics/toiletries, household detergents, pharmaceuticals, foods,agricultural and veterinary products, and ethylene glycol-basedantifreeze coolants. It is formed as a reaction byproduct during themanufacturing of ethoxylated surfactants. Manufacturers can remove mostof the 1,4-dioxane in consumer products through a vacuum strippingprocess. However, this process is costly and requires steam which can becapital intensive. As such, there exists a need to create a new methodof removing contaminants, like 1,4-dioxane from already ethoxylatedsurfactants.

SUMMARY OF THE INVENTION

In one example, a method of reducing the amount of a chemicalcontaminant in a composition, comprises; a) providing an initial feedsupply comprising a composition comprising an active and a chemicalcontaminant and, optionally, a solvent; b) providing a nanofilter; c)filtering the initial feed supply through the nanofilter to form aretentate comprising at least a portion of the active and a filtratecomprising at least a portion of the chemical contaminant and at least aportion of the solvent; and d) subjecting the filtrate to reverseosmosis to form a reverse osmosis permeate and a reverse osmosisconcentrate comprising at least a portion of the chemical contaminant.

In another example, a method of removing 1,4-dioxane from a surfactantcomposition comprising a surfactant and water, comprises: a) filteringthe surfactant composition through a nanofilter which filters outchemicals with a weight average molecular weight below about 250 Da toform a retentate which comprises at least a portion of the surfactantand a filtrate which comprises at least a portion of the 1,4-dioxane andat least a portion of the water; and b) subjecting the filtrate toreverse osmosis to form a reverse osmosis permeate and a reverse osmosisconcentrate comprising at least a portion of the chemical contaminant.

These and other potential incarnations will be discussed in more detailbelow.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a process schematic of a method of removing a chemicalcontaminant.

The drawing is illustrative in nature and not intended to be limiting ofthe invention.

DETAILED DESCRIPTION OF THE INVENTION

Features and benefits of the present invention will become apparent fromthe following description, which includes examples intended to give abroad representation of the invention. Various modifications will beapparent to those skilled in the art from this description and frompractice of the invention. The scope is not intended to be limited tothe particular forms disclosed and the invention covers allmodifications, equivalents, and alternatives falling within the spiritand scope of the invention as defined by the claims.

As used herein, the articles including “the,” “a” and “an” when used ina claim or in the specification, are understood to mean one or more ofwhat is claimed or described.

As used herein, the terms “include,” “includes” and “including” aremeant to be non-limiting.

The term “substantially free of” or “substantially free from” as usedherein refers to either the complete absence of an ingredient or aminimal amount thereof merely as impurity or unintended byproduct ofanother ingredient. A composition that is “substantially free” of/from acomponent means that the composition comprises less than about 0.5%,0.25%, 0.1%, 0.05%, or 0.01%, or in 100 ppm, 1 ppm, even 0%, by weightof the composition, of the component.

As used herein the phrases “detergent composition” and “cleaningcomposition” are used interchangeably and include compositions andformulations designed for cleaning soiled material. Such compositionsinclude but are not limited to, laundry cleaning compositions anddetergents, shampoo, body wash, hand cleanser, facial cleanser, fabricsoftening compositions, fabric enhancing compositions, fabric fresheningcompositions, laundry prewash, laundry pretreat, laundry additives,spray products, dry cleaning agent or composition, laundry rinseadditive, wash additive, post-rinse fabric treatment, ironing aid, dishwashing compositions, hard surface cleaning compositions, unit doseformulation, delayed delivery formulation, detergent contained on or ina porous substrate or nonwoven sheet, and other suitable form s that maybe apparent to one skilled in the art in view of the teachings herein.Such compositions may be used as a pre-laundering treatment, apost-laundering treatment, or may be added during the rinse or washcycle of the laundering operation.

As mentioned above, compositions can contain contaminants which are notpreferred by the manufacturer and/or user. These contaminants can bechemical in nature, like an unwanted by-product, reaction product, etc.or physical in nature, like a particle, dust, dirt, etc. Removingcontaminants from a composition can be costly and can make a productfiscally unviable. One chemical contaminant in which there is aninterest in removing from products is 1,4-dioxane.

Previous attempts to remove 1,4-dioxane from a surfactant pasteutilizing a process called vacuum stripping. In this system, steam isused under vacuum to separate 1,4-dioxane from the surfactant paste.This process is burdensome as it requires careful control of conditionslike temperature and pressure to have a successful outcome and requiresa lot of energy as it requires an influx of steam throughout theprocess. Thus, there is room for improvement in methods of removingchemical contaminants, like 1,4-dioxane.

Present inventors have discovered that chemical contaminants, likedioxane, can be removed through a nanofiltration process. Thenanofiltration process utilizes weight average molecular weight tofilter the unwanted chemical contaminant from the product. The processallows for a wide variety of processing conditions which can be adjustedbased on the targeted chemical contaminant and the product in which itis contained. These will be discussed in more detail below.

From a composition standpoint, this process can include an initial feedcomposition. The initial feed composition likely includes an active, asolvent, a contaminant, and/or one or more minor materials. The initialfeed composition is discussed in more detail below.

Initial Feed Composition

The initial feed composition comprises one or more solvents, a desiredactive, and one or more contaminants. The solvent may come in with thedesired active, be separately added, or both. The initial feedcomposition may also comprise one or more minor materials. The initialfeed may also comprise a surfactant composition which comprisessurfactant and water. As staled above, it has been surprisingly foundthat through the method described below incorporating nanofiltration,one can reduce the level of contaminants from an initial feedcomposition in comparison to the level of active in the composition.Without being bound by theory, it is believed that by selectivelychoosing the right solvents fora specific contaminant and the rightfiltration membrane, one can create a process wherein the solvent andthe contaminant can be at least partially removed to form a filtratewhile maintaining the substantial majority of the active to create aretentate. One can then either, recirculate the remaining retentatethereby increasing the percentage of active in the retentate and/or runthe retentate through additional filtration columns. Further, one mayadd additional contaminant free solvent to the retentate therebyincreasing ratio of solvent to active while reducing the ratio ofcontaminant to solvent in the retentate. The retentate with contaminantfree solvent may then be filtered additionally. This process mayrecirculate until a desired ratio of solvent to active and a desiredratio of contaminant to solvent or to active is reached. One of ordinaryskill in the art would understand that while the focus is on solvent,active, and contaminant, the composition may comprise more than oneactive, more than one contaminant, and other minors. As such, what isdescribed above and below serves as an example utilizing a solvent inrelation to an active and a contaminant as an illustrative example.

Solvents

Solvents may comprise water, organic solvents such as, for example,ethanol, propane diol, glycerin ethoxylate, glycerin propoxate, C₁-C₄alkanolamine, and glycerol, or combinations thereof. C₁-C₄ alkanolaminescan include, for example, monoethanolamine, triethanolamine, or acombination thereof. The solvent may have a weight average molecularweight about the same as or less than the target chemical contaminant.For example, the solvent may have a weight average molecular weight ofabout 400 Da or less, about 300 Da or less, about 250 Da or less, about200 Da or less, about 150 Da or less, about 100 Da or less, about 50 Daor less, about 25 Da or less, or about 10 Da or less.

Minor Materials

The initial feed composition may also comprise one or more minormaterials. Minor materials may comprise, for example, salts, biocides,and/or buffers. Nonlimiting examples include sodium sulfates and sodiumhydroxide.

Contaminant

The contaminant may be any chemical compound that is deemed undesirablein a final formulation. For example, the contaminant may be 1,4 dioxane,dimethyl dioxane, diethylene oxide sulfate, or a combination thereof.The contaminant may have a weight average molecular weight about theless than the target active. For example, the solvent may have a weightaverage molecular weight of about 400 Da or less, about 300 Da or less,about 250 Da or less, about 200 Da or less, about 150 Da or less, about100 Da or less, about 50 Da or less, about 25 Da or less, or about 10 Daor less.

Active

The active may be any chemical composition that has commercial valuewhich has a chemical contaminant. The active may be, for example, anethoxylated surfactant, a sulfated ethoxylated surfactant, anethoxylated polymer, a propoxylated surfactant, a sulfated propoxylatedsurfactant, a propoxylated polymer, or a combination thereof. The activemay be an alkoxylated polyamine compounds. The active may be azwitterionic polyamine. The active may, for example, have a weightaverage molecular weight of about 250 Da to about 1000 Da, about 300 Dato about 750 Da, about 300 Da to about 500 Da, or about 300 Da to about400 Da.

Ethoxylated Surfactant

The active may be an ethoxylated surfactants or a sulfated ethoxylatedsurfactant. Detergent compositions can contain surface activeingredients (sometimes referred to as “detergent active ingredients” or“detergent actives”), which may be neutralized salts of acids produced,for example, by sulfating or sulfonating C₈-C₂₀ organic materials and,preferably, C₁₀-Cis organic materials, such as, for example, fattyalcohols, alkoxylated fatty alcohols, ethoxylated fatty alcohols, alkylbenzenes, alpha olefins, methyl esters, alkyl phenol alkoxylates, andalkyl phenol ethoxylates. The process of making detergent actives fromthe acid form is typically performed in a solvent, such as water and/oralcohol. The resulting detergent material may be a paste, a solution, ora slurry of various components. (The term detergent “paste” as usedhereinafter is meant to include detergent solutions, slurries andpastes). Final detergent compositions are made from such detergentpastes.

Fatty alcohol ethoxy sulfates (AES) is a mild surfactant that generatesconsiderable foam and has excellent degreasing properties. It is used inpersonal care products, such as shampoo and body wash, and liquid dishcleaners, for example. Since it is derived from fatty alcohol it can bemade from natural oils, for example coconut oil. It can also be madefrom synthetic alcohol.

1,4-dioxane is a by-product formed largely during the sulfation processof making fatty alcohol alkoxy sulfates (AES) in relatively smallamounts. The 1,4-dioxane remains in the sulfated AES paste and othersubsequent compositions that contain it. Dioxane has come underincreasing scrutiny by consumer groups and regulatory bodies. There isthus a need for minimizing 1,4-dioxane in sulfated products.

Technology for minimizing 1,4-dioxane formation has been reported in theliterature dating back decades. Prior studies report steps that can betaken in the sulfation process to minimize the amount of 1,4-dioxanethat forms. Reducing the SO₃ gas concentration from 4% to 2.5%, forexample, has a dramatic effect and cuts the amount of 1,4-dioxane thatforms in half. Less dramatic benefits come from running at low moleratios of S0₃:feed so that conversion of the feed to the sulfatedproduct is less complete. These changes have a dramatic impact on theproduction capacity and cost-efficiency of a sulfation plant. Moves suchas these cut the plant capacity by as much as 50%.

Alkoxylated fatty alcohols are not “pure” materials but are mixtures ofhomologous molecules that contain different amounts of ethylene oxide,for example. The addition of ethylene oxide into fatty alcohols has longbeen done to produce nonionic surfactants. These have many uses inconsumer products. A typical nonionic ethoxylated fatty alcohol (AE) canbe referred to as a nominal “3-mole AE”, meaning that it has on average3 moles of ethylene oxide reacted with each mole of alcohol. In fact,the product will contain some of the primary alcohol with no EO added,some 1-EO, some 2-EO, some 3-EO, some 4-EO and so forth up thehomologous series. Thus, most manufacturers name their AE by describingthe fatty alcohol and the average number of EO added. The amount of1,4-dioxane that forms upon sulfation with air-SO₃ gas increases withthe EO content of the AE feed. To minimize the formation of 1,4-dioxanesome manufacturers have decided to shift the average EO content to anumber less than 2 in an attempt to reduce the amount of 1,4-dioxanethat forms. This choice may result in a reduction of 1,4-dioxane, buttrading of the optimum EO content in the AES for product performance.[0045] The present inventors recognized that modifying the sulfationprocess to try to reduce the amount of 1,4-dioxane would not efficientlyprovide the means to eliminate 1,4-dioxane or to reduce it to aninsignificant concentration; instead, the present inventors created aprocess and embodiments of suitable apparatus to physically andselectively remove 1,4-dioxane from the AES following sulfation, andprior to final product formulation when a dilute product is desired.

In the following description, the primary dioxane component referred tois 1,4-dioxane, although other dioxane isomers are also contemplated.Thus, the dioxane component can include one or more of 1,2-dioxane,1,3-dioxane, and 1,4-dioxane.

As mentioned above, the undesirable byproduct, 1,4-dioxane, is madeduring the sulfation process. A proposed mechanism for the formation of1,4-dioxane is for a molecule of ethoxysulfuric acid to form a complexwith a molecule of SO₃. A rearrangement occurs, forming anewethoxysulfuric acid with two fewer ethylene oxide equivalent units and1,4-dioxane which is complexed with an SO₃. The SO₃ can be released fromthe 1,4-dioxane and react to form ethoxysulfuric acid or recycle throughthis process and generate another molecule of 1,4-dioxane.

In a process described herein, the feedstock paste optionally can be anethoxylated fatty alcohol sulfate paste.

A common feedstock material that can be used in the method describedherein is sodium ethoxysulfate (AES) with 0.8 to 3 moles of ethoxylationwith ethylene oxide (EO) per mole of fatty alcohol. The fatty alcoholcarbon chain length is typically in the range of C₁₂ to C₁₆ and can bethe made from a naturally occurring material or can be purely syntheticor any combination thereof. The degree of ethoxylation with ethyleneoxide can be in the range of 0.5 to 50 moles of EO to mole of fattyalcohol, for example in a range of 1 to 12, or 3 to 7, for the purposesof sulfation to ethoxysulfuric acid and subsequent neutralization of theacid. Neutralization can be with sodium, potassium and ammonium types(e.g., TEA) on anionic bases, for example. The molecular weight forexample of a sodium ethoxysulfate (3 moles of EO) will be in the rangeof 442 Daltons. The process described herein for removing dioxane is notconstrained by the source of the carbon chain, the degree ofethoxylation, or the neutralizing agent.

In a process described herein, the process optionally can be performedto yield a composition having a ratio of contaminant, to active ofbetween 0:100 and 15:85, such as for example 1:99, 2:98, 3:97, 4:96, 5;95, 6:94, 7:93, 8:92, 9:91, 10:90, 11:89, 12:88, 13:87, or 14:86. In oneexample, this ratio is of dioxane to sulfated ethoxy surfactant.

In a process described herein, the process optionally can be performeduntil the total % of contaminant, like dioxane, in the composition isless than 10%, such as, for example, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, orless than 1% such as, between 0.0001% and 1% of the total composition.

In a process described herein, the process optionally can be performedto yield a concentrated product having a water content of 25 wt. % orless, or 15 wt. % or less, or 5 wt. % or less, or 2 wt. % or less.

In a process described herein, the process optionally can be performedto remove a dioxane component which is 1,4-dioxane.

Alkoxylated Polyamine Compounds

The active may be an alkoxylated polyamine compounds. Alkoxylatedpolyamine compounds are known to deliver cleaning and/or whiteningbenefits, for example soil anti-redeposition benefits. However, it hassurprisingly been discovered that alkoxylated poly amine compounds canoperate synergistically with sulfated surfactants at acidic pHs toprovide surfactant stability benefits in addition to cleaning and/orwhitening benefits. It is believed that the polyamines inhibit the rateof sulfated surfactant hydrolysis in low pH systems by interrupting H⁺access to the interface and/or by interrupting interaction among thesulfated surfactants.

In some aspects, the compositions of the present disclosure comprisefrom about 0.01%, or from about 0.05%, or from about 0.1%, or from about0.5%, or from about 0.8%, or from about 1.0%, or from about 1.5%, toabout 2%, or to about 2.5%, or to about 3%, or to about 5%, or to about10%, or to about 15%, or to about 20%, by weight of the composition ofalkoxylated polyamines. The composition may comprise mixtures ofalkoxylated polyamines.

The alkoxylated polyamine compound may have a weight average molecularweight of from about 200 to about 60,000, or to about 20,000, or toabout 10,000 Daltons. In some aspects, the weight average molecularweight is from about 350 to about 5000, or to about 2000, or to about1000 Daltons. In some aspects, the alkoxylated polyamine comprises apolyethyleneimine (PEI) backbone, where the backbone has a weightaverage molecular weight of from about 200 to about 1500, or of about400 to about 1000, or of about 500 to about 800, or of about 600Daltons.

The polyamines of the present disclosure are suitable for use in liquidlaundry detergent compositions, inter alia, gels, thixotropic liquids,and pourable liquids (i.e., dispersions, isotropic solutions).

In some aspects, the alkoxylated polyamine compound comprises one ormore alkoxylated compounds having at least two alkoxylated amine, imine,amide or imide groups.

Preferred are compounds having at least two alkoxylated amine groups,where the alkoxylated amine groups comprise alkoxylation groups.

The alkoxylation groups may have one or more alkoxylates, typically morethan one, thus forming a chain of alkoxylates, or polyalkoxylationgroup. The compound may have two alkoxylation groups or chains,preferably at least 4 or even at least 7 or even at least 10 or even atleast 16. Preferred is that the alkoxylation groups are polyalkoxylationgroups, each independently having an average alkoxylation degree of atleast about 5, more preferably at least about 8, preferably at leastabout 12, up to preferably about 80 or even to about 50 or even to about25. The (poly)alkoxylation is preferably a (poly)ethoxylation and/or(poly)propoxylation.

Thus, preferred is that the alkoxylation group comprises apolyethoxylation group, a polypropoxylation group, apolyethoxylation/polypropoxylation group, or mixture thereof.

The alkoxylated polyamine compound is preferably a polyamide, polyimideor more preferably a polyamine or polyimine compound, whereby theseamide, imide, amine or imine units are present as backbone of thepolymer, forming the chain of repeating units. Preferably, thesepolymers have at least 3 or even 4 or even 5 amide, imide, amine orimine units. It may be preferred that only some of the amine or imineare alkoxylated. It may be preferred that the backbone has alsoside-chains containing amide, imide, amine or imine group s, which maybe alkoxylated. In some aspects, the polyamine comprises apolyalkylamine backbone. The polyalkylamine may comprise C2 alkylgroups, C3 alkyl groups, or mixtures thereof. In some aspects, the polyamine has a polyethyleneimine (PEI) backbone. Preferred PEI backbones ofthe polyamines described herein, prior to alkoxylation, have the generalformula:

where n+m is equal to or greater than 10, or 12, or 14, or 18, or 22,and where B represents a continuation of this structure by branching.

Preferred polyamines include substantially noncharged, low molecularweight, water soluble, and lightly alkoxylated ethoxylated/propoxylatedpolyalkyleneamine polymers, such as those described in U.S. Pat. No.5,565,145, incorporated herein by reference. By “lightly” is meant thepolymers of this invention average from about 0.5 to about 10alkoxylations per nitrogen. By “substantially noncharged” is meant thatthere is no more than about 2 positive charges for every 40 nitrogenspresent in the backbone of the polyalkyleneamine polymer.

Particularly preferred polyamines include ethoxylated/propoxylatedpolyalkylamine polymers that are ethoxylated C₂-C₃ polyalkyleneamines,ethoxylated C₂-C₃ polyalkyleneimines, and mixtures thereof, for exampleethoxylated polyethyleneamines (PEAs) and ethoxylated polyethyleneimines(PEIs). In the poly alkyleneimines and polyalkyleneamines, each hydrogenatom attached to each nitrogen atom represents an active site forsubsequent ethoxylation. The PEIs used in preparing some preferredcompounds can have a molecular weight of at least about 600 prior toethoxylation, which represents at least about 14 units. Preferred areethoxylated polyethyleneimines, preferably having an averageethoxylation degree per ethoxylation chain of from about 15 to about 25,and a molecular weight of from about 1000 to about 2000 Daltons. Apreferred polyamine is PEI600 E20. Also preferred are ethoxylatedtetraethylene pentaimines. In some aspects, the molecular averagemolecular weight of the ethoxylated polyethyleneamines and/or theethoxylated polyethylemeimines are from about 8000 to about 25,000, orfrom about 10,000 to about 20,000, or from about 12,000 to about 15,000,or about 14,000 g/mol.

Highly preferred alkoxylated polyamine compounds are ethoxylatedpolyamine compounds of the following structures:

Also highly preferred are ethoxylated tetraethylene pentaamine.

Zwitterionic Polyamine

The active may be a zwitterionic polyamine. Preferably, the zwitterionicpolyamine is selected from zwitterionic polyamines having the followingformula:

R is C3-C20 preferably C5-C10 more preferably C6-C8 linear or branchedalkylene, and mixtures thereof, most preferably linear C6.

R¹ is an anionic or partially anionic unit-capped polyalkyleneoxy unithaving the formula: —(R2O)xR3, wherein R2 is C2-C4 linear or branchedalkylene, and mixtures thereof, preferably C2 or branched C3 andmixtures thereof, more preferably C2 (ethylene); R3 is hydrogen, ananionic unit, and mixtures thereof, in which not all R3 groups arehydrogen; x is from about 5 to about 50, preferably from about 10 toabout 40, even more preferably from about 15 to about 30, mostpreferably from about 20 to about 25. A preferred value for x is 24,especially when R¹ comprises entirely ethyleneoxy units. Depending uponthe method by which the formulator chooses to form the alkyleneoxyunits, the wider or narrower the range of alkyleneoxy units present. Theformulator will recognize that when ethoxylating a zwitterionicpolyamine, only an average number or statistical distribution ofalkyleneoxy units will be known. x values highlighted represent averagevalues per polyalkoxy chain. Preferably the range of alkyleneoxy unitswithin the zwitterionic polyamine is plus or minus two units, morepreferably plus or minus one unit. Most preferably each R¹ groupcomprises about the same average number of alkyleneoxy units.Non-limiting examples of R3 anionic units include —(CH2)pCO2M;—(CH2)qSO3M; —(CH2)qOS03M; —(CH2)qCH(SO2M)-CH2SO3M;—(CH2)qCH(OS02M)CH2OSO3M; —(CH2)qCH(SO3M)CH2SO3M; —(CH2)pP03M; —P03M;—SO3M and mixtures thereof; wherein M is hydrogen or a water solublecation in sufficient amount to satisfy charge balance. Preferred anionicunits are —(CH2)pC02M; —SO3M, more preferably —SO3M (sulfonate group).The indices p and q are integers from 0 to 6, preferably 0 to 2, mostpreferably 0. For the purposes of the present invention, all M units,can either be a hydrogen atom or a cation depending upon the formisolated by the artisan or the relative pH of the system wherein thecompound is used. Non-limiting examples of preferred cations includesodium, potassium, ammonium, and mixtures thereof.

Q is a quaternizing unit selected from the group consisting of C1-C30linear or branched alkyl, C6-C30 cycloalkyl, C7-C30 substituted orunsubstituted alkylenearyl, and mixtures thereof, preferably C1-C30linear or branched alkyl, even more preferably C1-C10 or even C1-C5linear or branched alkyl, most preferably methyl; the degree ofquaternization preferably is more than 50%, more preferably more than70%, even more preferably more than 90%, most preferably about 100%.

X is an anion present in sufficient amount to provide electronicneutrality, preferably a water soluble anion selected from the groupconsisting of chlorine, bromine, iodine, methylsulfate, and mixturesthereof, more preferably chloride. To a great degree, the counter ion Xwill be derived from the unit which is used to perform thequaternization. For example, if methyl chloride is used as thequaternizing agent, chlorine (chloride ion) will be the counter ion X.Bromine (bromide ion) will be the dominant counter ion in the case wherebenzyl bromide is the quaternizing reagent.

n is from 0 to 4, preferably 0 to 2, most preferably 0.

Preferably from about 10% to about 100%, more preferably from about 20%to about 70%, even more preferably from 30% to about 50%, mostpreferably from about 35% to about 45% of the R3 groups are an anionicunit, preferably a sulfonate unit, the remaining R3 units beinghydrogen.

Particularly preferred zwitterionic polyamines are zwitterionichexamethylene diamines according to the following formula:

R is an anionic or partially anionic unit-capped polyalkyleneoxy unithaving the formula: —(R20)_(x)R3 wherein R2 is C2-C4 linear or branchedalkylene, and mixtures thereof, preferably C2 or branched C3 andmixtures thereof, even more preferably C2 (ethylene); R3 is hydrogen, ananionic unit, and mixtures thereof, in which not all R3 groups arehydrogen; x is from about 5 to about 50, preferably from about 10 toabout 40, even more preferably from about 15 to about 30, mostpreferably from about 20 to about 25. A preferred value for x is 24,especially when R comprises entirely ethyleneoxy units. Depending uponthe method by which the formulator chooses to form the alkyleneoxyunits, the wider or narrower the range of alkyleneoxy units present. Theformulator will recognize that when ethoxylating a zwitterionicpolyamine, only an average number or statistical distribution ofalkyleneoxy units will be known. x values highlighted represent averagevalues per polyalkoxy chain. Preferably the range of alkyleneoxy unitswithin the zwitterionic polyamine is plus or minus two units, morepreferably plus or minus one unit. Most preferably each R groupcomprises about the same average number of alkyleneoxy units.Non-limiting examples of R3 anionic units include —(CH2)pCO2M;—(CH2)qSO3M; —(CH2)qOS03M; —(CH2)qCH(SO2M)-CH2SO3M;—(CH2)qCH(OS02M)CH2OSO3M; —(CH2)qCH(SO3M)CH2SO3M; —(CH2)pP03M; —P03M;—SO3M and mixtures thereof; wherein M is hydrogen or a water solublecation in sufficient amount to satisfy charge balance. Preferred anionicunits are —(CH2)pC02M; —S03M, more preferably —S03M (sulfonate group).The indices p and q are integers from 0 to 6, preferably 0 to 2, mostpreferably 0. For the purposes of the present invention, all M units,can either be a hydrogen atom or a cation depending upon the formisolated by the artisan or the relative pH of the system wherein thecompound is used. Non-limiting examples of preferred cations includesodium, potassium, ammonium, and mixtures thereof.

Q is a quaternizing unit selected from the group consisting of C1-C30linear or branched alkyl, C6-C30 cycloalkyl, C7-C30 substituted orunsubstituted alkylenearyl, and mixtures thereof, preferably C1-C30linear or branched alkyl, even more preferably C1-C10 or even C1-C5linear or branched alkyl, most preferably methyl; the degree ofquaternization preferably is more than 50%, more preferably more than70%, even more preferably more than 90%, most preferably about 100%.

X is an anion present in sufficient amount to provide electronicneutrality, preferably a water soluble anion selected from the groupconsisting of chlorine, bromine, iodine, methylsulfate, and mixturesthereof, more preferably chloride. To a great degree, the counter ion Xwill be derived from the unit which is used to perform thequaternization. For example, if methyl chloride is used as thequaternizing agent, chlorine (chloride ion) will be the counter ion X.Bromine (bromide ion) will be the dominant counter ion in the case wherebenzyl bromide is the quaternizing reagent.

Preferably from about 10% to about 100%, more preferably from about 20%to about 70%, even more preferably from 30% to about 50%, mostpreferably from about 35% to about 45% of the R3 groups are an anionicunit, preferably a sulfonate unit, the remaining R3 units beinghydrogen.

Most preferred compound is the zwitterionic hexamethylene diaminerepresented by the following formula:

in which approximately 40% of the polyethoxy groups are sulfonated, theremaining polyethoxy groups being hydrogen capped. The degree ofquaternization preferably is more than 90%, most preferably about 100%.Preferably the water soluble counter-anion is selected from the groupconsisting of chlorine, bromine, iodine, methylsulfate, and mixturesthereof, more preferably chloride.

The described zwitterionic polyamines can be made using techniquespreviously described in the art, and as such those skilled in the artwould understand how to produce such compounds. The polyamine is firstalkoxylated for example ethoxylated with ethylene oxide, followed by aquaternization step for example by reacting the alkoxylated polyaminewith dimethylsulfate, and finally an anionic group substitution step forexample by reacting the quaternized alkoxylated polyamine withchlorosulfonic acid.

Filtration

Unexpectedly, it has been discovered that the nanofiltration process canbe used successfully to eliminate or reduce the content of certaincontaminants or impurities which are normally contained in an initialfeed while being able to isolate the active or the surfactant. Forexample, dioxane can be removed from an initial feed containing anethoxylated sulfate surfactant and the surfactant isolated for furtherprocessing or use.

Because of the simplicity of the process under this invention, thispurification method offers certain advantages versus other physical orchemical processes because it does not require introduction of any otherelement in the solutions to be purified.

As shown in FIG. 1, the process 100 comprises introducing an initialfeed 102 composition comprising one or more solvents, a desired active,and one or more contaminants to a feed tank 110. The initial feedcomposition may be at any workable active concentration, pH, andtemperature. The active concentration of the initial feed can beimpacted, for example, by viscosity of the initial feed, stability ofthe initial feed at a given concentration, desired efficiency ofthroughput, etc. For example, some actives may separate out above orbelow a particular concentration. Likewise, the viscosity of the initialfeed needs to be such that it can be run through the nanofilter with thedesired efficiency and avoiding excessive clogging or other processingissues. These and any other relevant factors can be balanced todetermine the best selection for concentration of the particular initialfeed. The initial feed can have an active concentration of, for example,about 5% to about 45%, about 5% to about 40%, about 5% to about 35%,about 5% to about 30%, about 10% to about 30%, and/or about 15% to about25%. The initial feed my have a viscosity, for example, of about 1200 cPor less; about 1000 cP or less; about 500 cP or less; about 300 cP orless; from about 25 cP to about 1000 cP; and/or from about 50 cP toabout 750 cP.

The pH of the initial feed can impact things like stability of theinitial feed, selection of the nanofilter, and the need for a biocide,etc. Selection of these parameters will depend on the active in theinitial feed and the needs of the manufacturer. For example, if anactive is stable at a higher pH (above 10) and the manufacturer desiresto avoid the use of biocides, then that active can be in an initial feedthat is at a high pH. The other consideration for pH is that of thenanofilter. The material(s) use in the making of the nanofilter willimpact its ability to perform at a given pH. In addition, if utilized atlow or high pH, the life span of the nanofilter may be negativelyimpacted. Thus, the pH of the initial feed can be from about 3 to about14, about 4 to about 13, about 5 to about 12, about 6 to about 12, about7 to about 12, about 8 to about 12, about 9 to about 12, about 10 toabout 12, about 11 to about 12, or about 10 or more.

The temperature of the initial feed can also impact the ability to orefficiency of filtering of the chemical contaminant. For example, at alower temperature, an initial feed may be too viscous to filter.Alternatively, at a high temperature, the active or nanofilter maydegrade. Temperature may also be selected for convenience. If aparticular active is delivered at a higher temperature fortransportation reasons, that temperature can be maintained so long as itis compatible with the filtering system. The initial feed can be heatedor cooled as desired to reach the target temperature for filtering. Thetemperature of the initial feed may be, for example, from about 20° C.to about 60° C., from about 25° C. to about 55° C., from about 25° C. toabout 50° C., from about 30° C. to about 50° C., and/or from about 40°C. to about 50° C. The specific description below focuses on the use ofan ethoxylated surfactant paste and the filtering of 1,4-dioxane, butany suitable active and chemical contaminant can be substituted.

The initial feed may be, for example, an active comprising anethoxylated surfactant paste that includes at least 5% of AES as theactive, preferably about 15 wt % to about 25 wt % of the active; wateras the solvent, and 1,4 dioxane as the chemical contaminant. The initialfeed is at a temperature of about 40° C. to about 50° C. and a pH ofabout 11 to about 13. The initial feed is put into the feed tank 110.The feed tank 110 is connected to a filtration column 112 via a pump114. The pump 114 pulls the initial feed from the feed tank and suppliesit to the filtration column 112. The filtration column 112 utilizes afiltration membrane (not shown).

The filtration membrane can be selected based on the properties of theinitial feed and the chemical contaminant, like weight average molecularweight, temperature, pH, and viscosity. A disparity in the molecularweight of the chemical contaminant and the active will allow for m oreefficient filtering. Here, where filtering the initial feed of AES withthe parameters noted above, a filter membrane which filters materialswith a weight average molecular weight below about 200 Daltons is used.This is selected as dioxane has a weight average molecular weight ofabout 88 Daltons and the active, AES has a molecular weight of >300Daltons. Additionally, where the solvent used is water, it has a weightaverage molecular weight of about 18 Da allowing it to be filtered withthe dioxane. Thus, by applying nanofiltration to ethoxylatedsurfactants, one can reduce the presence of 1-4, dioxane by filtering itout. The filtered water carrying the dioxane can then be replaced withwater that is dioxane free.

Selection of the size of the filter is thus based upon the weightaverage molecular weight of the materials which one is trying toseparate. For example, the nanofilter size can be selected so that itfilters a weight average molecular weight which includes the molecularweight of the chemical contaminant and excludes the molecular weight ofthe active. A nanofilter can, for example, filter materials with aweight average molecular weight of about 400 Da or less, about 300 Da orless, about 250 Da or less, about 200 Da or less, about 150 Da or less,or about 100 Da or less. The filtration column may be a single stage orhave multiple stages. Adding additional stages can increase theefficiency of the filtering process so that a lower number of passes canb e utilized.

Selection of the type of nanofiltration membrane can impact itsoperating life. For example, if the initial feed is of a high pH, thenthe nanofiltration membrane can be selected such that it will havesufficient operating life at the high pH. If the nanofiltrationmembrane's operating life is too short, this can result in a frequentneed for changing out the nanofiltration membrane which can be bothoperationally and fiscally difficult to manage. The nanofilter, forexample, can filter about 80% or more of the initial feed before needingto be replaced

When the initial feed is at a pH of 11 or more, for example, 11 to 13,suitable commercial membranes which can be used at this high pH caninclude, for example, the Synder®-NFS, AMS Technologies B-4022, Koch™SeIRO®, MPS 34, or a combination thereof.

The nanofilter may comprise any material or have any configuration whichworks in the system. For example, the nanofilter can comprise ceramic, apolymer, or a combination thereof. The membrane can comprise a hollowfiber, a tubular fiber, a spiral wound fiber, or a combination thereof.The nanofilter may be, for example, a spiral and/or contain a spiralelement.

The initial feed is passed through the filtration column under pressure.This helps to separate the chemical contaminant from the active. Theworking pressure of the system may range from about 8 to about 62kg/cm². In one example, the pressure is between 10 and 25 kg/cm². Thispressure is a product of the properties of the initial feed, the set-upof the system, selection of the membrane, and number of membranes (i.e.stages).

As the initial feed passes through the filtration column, a filtrate 104and a retentate 106 are formed. If this is the first pass of the initialfeed through the process then they are the initial filtrate and theinitial retentate. The filtrate 104 will contain the filtered chemicalcontaminant and a filtered solvent. It is expected the majority of thesolvent will be filtered solvent, but a portion of the solvent may be inthe retentate. The retentate will have a lower ratio by weight of thechemical contaminant to the active than the initial feed supply.

The filtrate can then go through a reverse osmosis process 115. Thereverse osmosis process is a purification process which then separatesthe chemical contaminant from the solvent. The chemical contaminantbecomes part of the reverse osmosis concentrate, while the solventbecomes part of the reverse osmosis permeate. In the case of AESdescribed above, it separates the 1,4-dioxane which becomes part of thereverse osmosis concentrate from the water which becomes part of thereverse osmosis permeate. Reverse osmosis can also remove low levels ortrave levels of organics carried over from the initial feed which willalso become part of the reverse osmosis concentrate. The use of thisprocess at this point does a few things. First, the chemical contaminantin the filtrate needs to be taken care of, meaning, it likely has to bedealt with in some fashion to allow for its disposal. Without reverseosmosis, this means the solvent which contains contaminant either needsto be cleaned and/or disposed of. Depending on the contaminant, the typeof solvent, and the amount of solvent, this can be an expensiveendeavor. It can also add to a lot of waste of solvent if it is unableto be reused. Second, by separating the chemical contaminant, organicimpurities, and the solvent, the solvent can be reused. For example, thesolvent can be added back into the beginning of the filtration processas part of a new initial feed as a solvent or can be used in a differentprocess. Third, by concentrating the chemical contaminant, it allows formore efficient processing of the contaminant to render it appropriatefor disposal.

One way to prepare the filtered chemical contaminant in the filtrate orreverse osmosis concentrate for disposal is through the use ofadditional processing 116. This additional processing can be used todestroy or alter the chemical contaminant. This additional processingcan include, for example, advanced oxidation processing, Fentonreaction, photo-Fenton reaction, activated carbon adsorption, catalystprocessing, alcohol dehydration reaction, ozone treatment,ultra-violet/TiO₂ treatment, incineration, or a combination thereof.Catalysts which can be used to destroy a chemical contaminant caninclude, for example, calcium oxide, phosphorus pentoxide, chlorine,water and boron oxide with the following amounts of the components asexpressed in weight percent:calcium oxide 48.5 to 53.5, phosphoruspentoxide 42.5 to 46.5, chlorine 0.05 to 1.0, boron oxide 0.005 to 3.0,the balance being water. Such catalysts are described in, for example,GB2056421, GB2053871, and/or GB1078117. Catalysts may include calciumphosphate catalysts that may be used in the manufacture of isoprene fromisobutene and formaldehyde or by decomposition of 1,3 dioxanes. Afterthe chemical contaminant is put through the additional processing, anyrecovered solvent (i.e. processed solvent, for example, processed water)may be recycled back into the filtration system or disposed of asdesired

Depending on the efficiency of the process, there could still be morechemical contaminant in the initial or subsequent retentate 106 thandesired. If this is the case, the retentate 106 can be fed back to thefeed tank 110 and put through the filtering process again until a targetlevel of contaminant is reached. The retentate composition may bediluted back to the original concentration of active by adding solvent,for AES by adding water. The water may or may not be processed filtrateor recovered from the reverse osmosis process. Additional solvent 108may be added to the feed tank or in the line to change the ratio ofsolvent to contaminant. The additional solvent may be added at any timein the process to the initial feed composition 102 or to the retentate106, including and not limited to, before beginning the process, afterplacing the feed composition in the feed tank, after the pump, after thenanofilter, or continuously while the process is ongoing including whilethe process is ongoing and recycling the retentate and after the processhas stopped. Once the target level of contaminant is reached, theretentate may be removed from the process. This may be, for example, atleast a 90 wt % reduction in the contaminant from the starting level(i.e. before the filtration processing). The acts of filtering andadding solvent may be repeated, for example, until the process yields aconcentrated retentate having from about 18% to about 99% by weight ofactive.

The filtration process may be done in batch as shown below in theexample or in a continuous form by having a plurality of columns inseries. In addition, the process can be done as a continuousdiafiltration. As described above, additional solvent may be added atany time during the process to increase the ratio of solvent tocontaminant. The new composition, including the added contaminant freesolvent if any, may then be filtered thereby increasing the ratio ofactive to contaminant. At that time, additional contaminant free solventmay be added and the process can be repeated again. This may occur untilthe desired ratio of active to contaminant is reached. Further, asstated above, the initial feed stock may be filtered a plurality oftimes without adding contaminant free solvent.

EXAMPLE

The Nanofilter membrane used was NFS made by Synder Filtration. Thefiltration was done in a batch process. The composition contained 16.5%alkyl ethoxy sulfate in water and other solvents in water. The initialfeed is placed in a feed tank. Next, the composition was circulatedthrough the column containing the 1.8-inch nanofiltration membrane (1.95m²/membrane). The initial feed temperature was approximately 38° C. Theinitial feed pressure was 14 kg/cm².

The filtration process produced an initial filtrate and an initialretentate. The retentate was recirculated back to the feed tank. Thefiltrate containing water and dioxane contaminant was separatelycollected.

The flux of water with dioxane achieved was 42 l/m²/hr. The dioxanepassage through the membrane was close to 100% as the concentrationsanalyzed in the feed and filtrate were approximately the same at anygiven point in time. The surfactant passage was minimal as the filtratedid not produce any foam and foam would be expected to be present inwater if the surfactant were at a concentration greater than about 50ppm. The initial composition may be adjusted to a pH between pH 7 to pH8.

As shown in the example above, the filtration process produces aninitial filtrate and an initial retentate. After filtration, theretentate composition with a higher AES concentration may be recovered.The initial filtrate solution containing the 1,4-dioxane and water maybe recovered or may be discarded. The filtrate may be subjected toadditional processing to remove the dioxane from the solvent (water),explained further below. The treated filtrate water may then be recycledand reintroduced to the retentate to reduce the viscosity of theretentate through dilution.

Alternatively, the filtration process may repeat a new cycle until thefinal alkyl ethoxy concentration in the solution recovered under theseconditions is approximately 16.5% and is otherwise of similarcomposition as the initial solution but with at least about 90% lower 1,4-dioxane.

For example, an initial feed of 1,000 L Sodium Alkyl Ethoxy Sulfate at16.5% w/w, water, and 1,4-Dioxane at 150 ppm may be filtered through oneor more cycles until the 1,000 L filtered solution has Sodium AlkylEthoxy Sulfate at 16.5% w/w and 1,4-Dioxane at 15 ppm or lower.

Combinations

A) A method of reducing the amount of a chemical contaminant in acomposition, comprising; a) providing an initial feed supply comprisinga composition comprising an active and a chemical contaminant and,optionally, a solvent; b) providing a nanofilter; c) filtering theinitial feed supply through the nanofilter to form a retentatecomprising at least a portion of the active and a filtrate comprising atleast a portion of the chemical contaminant and at least a portion ofthe solvent; and d) subjecting the filtrate to reverse osmosis to form areverse osmosis permeate and a reverse osmosis concentrate comprising atleast a portion of the chemical contaminant.B) The method of paragraph B, wherein at least a portion of the reverseosmosis permeate is recycled for use as a solvent.C) The method of any of paragraphs A-B, wherein at least a portion ofthe reverse osmosis concentrate is further processed to destroy at leasta portion of the chemical contaminant in the reverse osmosisconcentrate.D) The method of paragraph C, wherein the process to destroy at least aportion of the chemical contaminant comprises advanced oxidationprocessing, Fenton reaction, photo-Fenton reaction, activated carbonadsorption, catalyst processing, alcohol dehydration reaction, ozonetreatment, ultra-violet/TiO₂ treatment, incineration, or a combinationthereofE) The method of any of paragraphs A-D, wherein the chemical contaminantcomprises 1,4-dioxane; dimethyl dioxane; diethylene oxide sulfate; or acombination thereof.F) The method of any of paragraphs A-E, wherein the initial feed has aviscosity of about 1000 cP or less; about 750 cP or less; about 500 cPor less; about 300 cP or less; from about 25 cP to about 1000 cP; and/orfrom about 50 cP to about 750 cP.G) The method of any of paragraphs A-F, wherein the initial feed has aviscosity of about 300 cP or less.H) The method of any of paragraphs A-G, wherein the nanofilter filters aweight average molecular weight which includes the molecular weight ofthe contaminant and excludes the molecular weight of the active.I) The method of any of paragraphs A-H wherein nanofilter filters aweight average molecular weight of about 250 Da or less; about 200 Da orless; about 150 Da or less; and/or about 100 Da or less.J) The method of any of paragraphs A-I, wherein the active comprises anethoxylated surfactant, a sulfated ethoxylated surfactant, anethoxylated polymer, a propoxylated surfactant, a propoxylated sulfatedsurfactant, a propoxylated polymer, or a combination thereof.K) The method of any of paragraphs A-J, wherein the initial feed has apH of about 10 or m ore; a pH of about 10 to about 14; a pH of about 11to about 13, about 11 to about 12.L) The method of any of paragraphs A-K, wherein the nanofilter canfilter about 80% or more of the initial feed before needing to bereplaced.M) The method of any of paragraphs A-L, wherein the solvent compriseswater, ethanol, propane diol, glycerol, glycerin ethoxylate, or acombination thereof.O) A method of removing 1,4-dioxane from a surfactant compositioncomprising a surfactant and water, comprising: a) filtering thesurfactant composition through a nanofilter which filters out chemicalswith a weight average molecular weight below about 250 Da, to form aretentate which comprises at least a portion of the surfactant and afiltrate which comprises at least a portion of the 1,4-dioxane and atleast a portion of the water and b) subjecting the filtrate to reverseosmosis to form a reverse osmosis permeate and a reverse osmosisconcentrate comprising at least a portion of the chemical contaminant.P) The method of paragraph 0, wherein the surfactant compositioncomprises from about 10% to about 40 wt %, from about 15% to about 25%by weight of the surfactant.Q) The method of any of paragraphs O-P, wherein the surfactant comprisesan ethoxylated surfactant, a sulfated ethoxylated surfactant, or acombination thereof; preferably a fatty alcohol ethoxy sulfate.R) The method of any of paragraphs O-Q, wherein at least a portion ofthe reverse osmosis permeate is recycled for reuse.S) The method of any of paragraphs O-R, wherein at least a portion ofthe reverse osmosis concentrate is further processed to destroy at leasta portion of the 1,4-dioxane in the reverse osmosis concentrate.T) The method of any of paragraphs 0-S, wherein the surfactantcomposition has a pH of about 11 to about 13.U) The method of any of paragraphs O-T, wherein the nanofilter filtersout chemicals with a weight average molecular weight below about 200 Daor below about 150 Da or below about 100 Da.

The dimensions and values disclosed herein are not to be understood asbeing strictly limited to the exact numerical values recited. Instead,unless otherwise specified, each such dimension is intended to mean boththe recited value and a functionally equivalent range surrounding thatvalue. For example, a dimension disclosed as “40 mm” is intended to mean“about 40 mm.”

It should be understood that every maximum numerical limitation giventhroughout this specification includes every lower numerical limitation,as if such lower numerical limitations were expressly written herein.Every minimum numerical limitation given throughout this specificationwill include every higher numerical limitation, as if such highernumerical limitations were expressly written herein. Every numericalrange given throughout this specification will include every narrowernumerical range that falls within such broader numerical range, as ifsuch narrower numerical ranges were all expressly written herein.

Every document cited herein, including any cross referenced or relatedpatent or application and any patent application or patent to which thisapplication claims priority or benefit thereof, is hereby incorporatedherein by reference in its entirety unless expressly excluded orotherwise limited. The citation of any document is not an admission thatit is prior art with respect to any invention disclosed or claimedherein or that it alone, or in any combination with any other referenceor references, teaches, suggests or discloses any such invention.Further, to the extent that any meaning or definition of a term in thisdocument conflicts with any meaning or definition of the same term in adocument incorporated by reference, the meaning or definition assignedto that term in this document shall govern.

While particular embodiments of the present invention have beenillustrated and described, it would be obvious to those skilled in theart that various other changes and modifications can be made withoutdeparting from the spirit and scope of the invention. It is thereforeintended to cover in the appended claims all such changes andmodifications that are within the scope of this invention.

What is claimed is: 1) A method of reducing the amount of a chemicalcontaminant in a composition, comprising; a) providing an initial feedsupply comprising a composition comprising an active and a chemicalcontaminant and, optionally, a solvent; b) providing a nanofilter; c)filtering the initial feed supply through the nanofilter to form aretentate comprising at least a portion of the active and a filtratecomprising at least a portion of the chemical contaminant and at least aportion of the solvent; and d) subjecting the filtrate to reverseosmosis to form a reverse osmosis permeate and a reverse osmosisconcentrate comprising at least a portion of the chemical contaminant.2) The method of claim 1, wherein at least a portion of the reverseosmosis permeate is recycled for use as a solvent. 3) The method ofclaim 1, wherein at least a portion of the reverse osmosis concentrateis further processed to destroy at least a portion of the chemicalcontaminant in the reverse osmosis concentrate. 4) The method of claim3, wherein the process to destroy at least a portion of the chemicalcontaminant comprises advanced oxidation processing, Fenton reaction,photo-Fenton reaction, activated carbon adsorption, catalyst processing,alcohol dehydration reaction, ozone treatment, ultra-violet/TiO₂treatment, incineration, or a combination thereof 5) The method of claim1, wherein the chemical contaminant comprises 1,4-dioxane; dimethyldioxane; diethylene oxide sulfate; or a combination thereof. 6) Themethod of claim 1, wherein the initial feed has a viscosity of about1000 cP or less. 7) The method of claim 1, wherein the initial feed hasa viscosity of about 300 cP or less. 8) The method of claim 1, whereinthe nanofilter filters a weight average molecular weight which includesthe molecular weight of the contaminant and excludes the molecularweight of the active. 9) The method of claim 8, wherein nanofilterfilters a weight average molecular weight of ab out 250 Da or less. 10)The method of claim 1, wherein the active comprises an ethoxylatedsurfactant, a sulfated ethoxylated surfactant, an ethoxylated polymer, apropoxylated surfactant, a propoxylated sulfated surfactant, apropoxylated polymer, or a combination thereof. 11) The method of claim1, wherein the initial feed has a pH of about 10 or more. 12) The methodof claim 11, wherein the nanofilter can filter about 80% or more of theinitial feed before needing to be replaced. 13) A method of removing1,4-dioxane from a surfactant composition comprising a surfactant andwater, comprising: a) filtering the surfactant composition through ananofilter which filters out chemicals with a weight average molecularweight below about 250 Da to form a retentate which comprises at least aportion of the surfactant and a filtrate which comprises at least aportion of the 1,4-dioxane and at least a portion of the water; and b)subjecting the filtrate to reverse osmosis to form a reverse osmosispermeate and a reverse osmosis concentrate comprising at least a portionof the chemical contaminant. 14) The method of claim 13, wherein thesurfactant composition comprises from about 10% to about 40 wt % of thesurfactant. 15) The method of claim 14, wherein the surfactant comprisesan ethoxylated surfactant, a sulfated ethoxylated surfactant, or acombination thereof. 16) The method of claim 15, wherein at least aportion of the reverse osmosis concentrate is further processed todestroy at least a portion of the 1,4-dioxane in the reverse osmosisconcentrate. 17) The method of claim 15, wherein the surfactantcomposition has a pH of about 11 to about
 13. 18) The method of claim15, wherein the nanofilter filters out chemicals with a weight averagemolecular weight below about 200 Da or below about 150 Da or below about100 Da.